Cyclobenzaprine is a centrally acting skeletal muscle relaxant used for the short-term management of acute, painful musculoskeletal conditions associated with muscle spasm. It is a synthetic pharmaceutical active ingredient belonging to the dibenzocycloheptene class and is structurally related to tricyclic compounds.
Cyclobenzaprine is supplied as an active pharmaceutical ingredient for pharmaceutical formulation and drug-development applications. The compound is commonly used in the manufacture of oral dosage forms, particularly tablets and extended-release capsules.
Cyclobenzaprine has the molecular formula C20H21N and a molecular weight of approximately 275.39 g/mol. The commonly used pharmaceutical salt is cyclobenzaprine hydrochloride.
Cyclobenzaprine produces its muscle-relaxant effect primarily through activity in the central nervous system. It reduces excessive somatic motor activity and helps relieve muscle spasm without directly acting on skeletal muscle fibers or the neuromuscular junction.
Its pharmacological profile includes centrally mediated muscle-relaxant activity together with anticholinergic and antihistaminic properties.
Cyclobenzaprine acts predominantly at the brainstem level and influences descending serotonergic pathways involved in the regulation of motor activity. This reduces tonic somatic motor activity and contributes to relief of painful muscle spasm.
Cyclobenzaprine does not directly block neuromuscular transmission. Its activity is therefore different from that of peripheral neuromuscular blocking agents.
Cyclobenzaprine is used as an adjunct to rest and physical therapy for the relief of muscle spasm associated with acute, painful musculoskeletal conditions.
It is generally intended for short-term treatment, because its clinical usefulness for prolonged treatment of chronic musculoskeletal conditions has not been established in the same manner as short-term therapy.
Cyclobenzaprine may be incorporated into different pharmaceutical dosage forms, including:
The final dosage form, strength and excipient system depend on the approved pharmaceutical product and applicable regulatory requirements.
Cyclobenzaprine hydrochloride is the hydrochloride salt form commonly used in pharmaceutical formulations. Salt formation can improve the handling and formulation characteristics of the active ingredient.
For manufacturing and regulatory purposes, the exact specification should identify whether the supplied material is Cyclobenzaprine free base or Cyclobenzaprine Hydrochloride.
Cyclobenzaprine API quality control may include testing for:
Analytical testing should be performed using validated methods appropriate for the material and intended pharmaceutical application.
Cyclobenzaprine intended for pharmaceutical manufacturing should be handled according to applicable GMP, quality-control and regulatory requirements. Manufacturing specifications should be established according to the intended market, applicable pharmacopoeial requirements and the manufacturer's approved product specification.
A Certificate of Analysis (CoA) should be provided for each commercial batch where applicable, containing the relevant test results and acceptance criteria.
Cyclobenzaprine API should be stored according to the manufacturer's approved storage conditions and packaging requirements. The material should be protected from conditions that may adversely affect its quality, including excessive moisture, heat and unsuitable environmental exposure.
Cyclobenzaprine API is relevant to pharmaceutical companies involved in formulation development, generic drug manufacturing, analytical research and pharmaceutical product development.
For commercial pharmaceutical applications, customers should verify the applicable grade, specification, regulatory documentation, analytical data and batch-specific CoA before use.
Cyclobenzaprine is a pharmaceutical active ingredient primarily associated with centrally acting muscle-relaxant activity. It is particularly relevant to formulations intended for the short-term relief of acute painful musculoskeletal muscle spasm.
Its established pharmaceutical form, cyclobenzaprine hydrochloride, is widely recognized in pharmaceutical development and formulation work. The API should be evaluated according to its specific salt form and applicable quality specification.
High-quality Cyclobenzaprine API should demonstrate consistent identity, purity, assay and impurity profile from batch to batch. Appropriate packaging, storage and analytical documentation help support reliable pharmaceutical formulation and manufacturing processes.
For pharmaceutical development, customers should consider documentation such as Certificate of Analysis, specification sheet, analytical method information, safety documentation and applicable regulatory documents according to their requirements.
| Parameter | Specification |
|---|---|
| Appearance | White to off-white crystalline powder |
| Identification | Conforms to Cyclobenzaprine identity by validated analytical methods |
| Assay (HPLC) | NLT 98.0% by HPLC |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| Heavy Metals | NMT 10 ppm |
| pH (1% Solution) | 2.0 – 4.0 |
| Individual Impurity | NMT 1.0% |
| Total Impurities | NMT 2.0% |
| Water Content | NMT 1.0% |
| Melting Point | Approximately 104–107°C |
| Solubility | Practically insoluble in water; soluble in alcohol and organic solvents |